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Mini-Phase Procedure (UV Line)
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Document Number: FEL-PR-08-001
Revision Number: Rev. 4, January 13, 2011 (C. Tennant)
Technical Custodian: Dave Douglas
Estimated Time to Perform: 30 minutes
Procedure Overview__________________________________________
A Miniphase of the FEL is required after an overnight shutdown or following a Controlled
Access. The Miniphase may also be necessary for machine recovery after degradation due
to slow drifts. The Miniphase sets the injector phases, sets the proper charge, phases the
linac, optimizes the wiggler and adjusts the pathlength. The procedure is comprised of:
Section 1.0 Verify the Correct Allsave Has Been Loaded
Section 2.0 Set the Charge to 60 pC
Section 3.0 Set the Relative Phase of the Drive Laser and Buncher
Section 4.0 Gang Phase the Laser-Buncher
Section 5.0 Set the Phase of Cavity 1-3
Section 6.0 Gang Phase the Linac
Section 7.0 Optimize the Bunch Length at the Wiggler
Section 8.0 Adjust the PathLength
Section 9.0 Appendix I - Required EPICS/MEDM screens
Prerequisites________________________________________________
1. The FEL Startup Procedure has been completed to the point the Miniphase
Procedure is referenced and directed to be performed.
Procedure Steps_____________________________________________
1.0
Verify the Correct All-Save Has Been Loaded
1. Load an appropriate All-Save. Unless specifically instructed otherwise (FLOG or FEL
Shift Plan) this should be either:
a. The “morning miniphase” (if setting up from the previous day), or
b. The current running setup or what should have been running for access recovery
or performance recovery.
NOTE: The point is to start with an intelligent All-Save.
2. Verify that all BLMs are unmasked.
3. Verify the DLPC is configured to produce tune-up beam.
NOTE: Tune-up beam is defined here as:
 Pulsed mode at 2 Hz
 250 μs macropulse
 4.6 MHz micropulse frequency
4. Confirm that tune-up beam exists with acceptable ghost pulses:
a. Inspect the drive laser Tekscope before opening the operator shutter.
b. Any of the SLMs can also be observed when the operator shutter is opened.
c. Is the machine in an acceptable tune-up mode at this point?
A. NO Stop and contact expert assistance YES Continue
5. Mask all BLMs, but only if the machine is in a tune-up mode and reasonably clean.
6. Open the Miniphase Combo screen (FEL Main Menu⇒Development⇒Miniphase Combo).
Figure 1-1: Screenshot of the Miniphase Combo screen.
2.0
Set the Charge to 60 pC
1. Set the charge to 60 pC as follows:
a. Adjust the drive laser polarizer (labeled “A” on Figure 1-1) to excite the Unser
monitor as observed on Tekscope B (green trace, channel 4) to 140 mV. Is there
sufficient charge as measured on Tekscope B?
A. NO Stop and contact expert assistance YES Continue
3.0
Set the Relative Phase of the Drive Laser and Buncher
1. Open the RF Injector Phase Monitor screen (FEL Main Menu⇒RF⇒Injector Phase Monitor).
2. B Volts for Qtr Cryo 4 should read 0.2275. If it does not, change the gradient in
zone 1 cavity 4 by steps of 0.01 MV/m until it does (labeled “B” on Figure 1-1).
NOTE: it takes several seconds for the value to update.
Figure 3-1: Screenshot of the RF Injector Phase Monitor.
3. Check the Beam Viewer Timing System (FEL Main Menu⇒Viewer⇒Beamviewer Timing
System) for proper configuration. The Timing Output button must be in the On
position for the Beamanizer application.
4. Map viewer ITV0F06 to Monitor 17.
5. While monitoring the Beamanizer image of ITV0F06, adjust the drive laser phase
(labeled “C” on Figure 1-1) to restore the beam to the standard ITV0F06 image (see
Figure 3-2).
NOTE: To load the standard image click “Off-line” on the Beamanizer and navigate
to C:\Documents and Settings\fella\Desktop\Beam Images\Mini phase images and select the
ITV0F06 image (the file must have the .pnm extension).
Figure 3-2: ITV0F06 as viewed with the Beamanizer.
6. Remove ITV0F06.
4.0
Gang Phase the Laser-Buncher
CAUTION: Do not use the laser-buncher gang phase for adjustment in this section.
1. Insert ITV0F04.
2. Map ITV0F04 to Monitor 17 using the video switcher controls.
3. Take the Beamanizer Off-line and load the proper ITV0F04 file. The file must have
the .pnm extension. Files are located at C:\Documents and Settings\fella\Desktop\Beam
Images\Mini phase images. The appropriate file will be specified in the Shift Plan.
4. Use the bars to frame the Off-line image.
5. Take the Beamanizer on-line. The present condition of the beam at ITV0F04 will be
displayed (see Figure 4-1).
Figure 4-1: ITV0F04 as viewed with the Beamanizer.
6. Adjust the laser phase and buncher phases in 1º increments, remembering to adjust
the laser phase 1º for every degree of buncher adjustment (labeled “D” on Figure 11). The goal is to adjust the phases such that the spot approximately matches the
preloaded shape boundaries.
7. Take the Beamanizer off-line.
8. Withdraw ITV0F04.
5.0
Set the Phase of Cavity 1-3
1. Insert ITV0F06.
2. Map ITV0F06 to Monitor 17 using the video switcher controls.
3. Take the Beamanizer Off-line and load the proper ITV0F06 file. The file must have
the .pnm extension. Files are located at C:\Documents and Settings\fella\Desktop\Beam
Images\Mini phase images. The appropriate file to use will be specified in the Shift Plan.
4. Use the bars to frame the off-line image.
5. Take the Beamanizer on-line. The present condition of the beam at ITV0F06 will be
displayed (see Figure 3-2).
6. Does the beam image match the preloaded image?
A. NO Set the increment on Cavity 1-3 phase slider to 0.1º (labeled “E” on
Figure 1-1) and adjust to match the preloaded image. The goal is to adjust
the phase so that the spot approximately matches the preloaded shape
boundaries YES Continue to Step 7.
C. If desired, save the beam image.
D. Take the Beamanizer Off-line.
E. Withdraw ITV0F06.
7. Section 3.0, Section 4.0 and Section 5.0 should be repeated after the completion of
Section 5.0 to ensure the symmetry of the drive laser phase is maintained. This may
involve an iterative process to achieve an acceptable solution to the three sections.
CAUTION: If Cavity 1-3 is changed by more than 0.5°, this section should be
repeated because the zero-crossing will be lost.
a. Has the symmetry of the drive laser phase been verified per Section 3.0 and an
acceptable solution reached for Sections 3.0, 4.0 and 5.0?
A. NO Go to Section 3.0, Set the Relative Phase of the Drive Laser and
Buncher and check Sections 3.0, 4.0 and 5.0 to ensure the drive laser phase
symmetry is maintained and injector phases are satisfactory YES Continue
8. Zero the RF Phase Monitor Relatives by pressing the Zero All Relatives on Injector
RF Phase Monitor and add a screen shot of the EPICS screen to the FLOG entry of
the Miniphase.
6.0
Gang Phase the Linac
NOTE: The average of the relative horizontal positions at IPM2F07 and IPM2F09 will
be used as an indication of proper phasing. These two BPMs are at dispersive
locations. The average of the two relative horizontal positions is an indication of the
machine energy.
1. Decrease the gang phase by 20º in Zone 2 (labeled “F” on Figure 1-1).
2. Note the change of the average BPM signal on the striptool. Did the average signal
change by less than 0.5 mm?
A. NO the XREL average changes more than 0.5 mm as the gang phase is
changed by 20º, the module is not properly phased. The relationship between
gang phases and linac energy gain is shown below in Figure 6-1. Follow the
steps below to phase the module:

If the XREL average drops when the gang phase is changed by 20º,
the gang phase is too negative. Add the 20º back and increase the
gang phase by a few tenths of a degree. Go back to Step 1 and repeat
the measurement.

If the XREL average increases when the gang phase is changed by
20º, the gang phase is too positive. Add the 20º back and decrease
the gang phase by a few tenths of a degree. Go back to Step 1 and
repeat the measurement.
Figure 6-1: Relationships of gang phase, beam position, and energy.
3. Restore the gang phase by adding 20º back and then go to Step 1 at the beginning
of this section and repeat for RF zones 3 and 4.
4. Go to Section 7.0, Optimize the Bunch Length at the Wiggler after the three zones
are properly phased.
7.0
Optimize the Bunch Length at the Wiggler
1. Change micropulse repetition frequency to 584 kHz and the macropulse length to 20
s (choose 50 s then select “Other” and enter “0.000020”).
2. Insert viewer ITV8F03. This is the viewer used with the Happek device.
3. Open the FEL Happek Interferometer -IR(Upstream) screen (FEL Main Menu⇒Data
Acq⇒ UV Happek) and click on the Setup button (see Figure 7-1).
Figure 7-1: Happek device screen.
4. Maximize the output of the Golay cell signal amplitude by adjusting the vernier cavity
gradient (labeled “G” on Figure 1-1). A step size of 0.01 MV/m should be used for
adjustments. See Figure 7-2 for typical scope display of the Golay cell.
NOTE: The output of the Golay cell, which is used in the Happek device, is always
connected to channel 1 of felscope01. The screen of the scope is usually shown on
Monitor 9 in the control room but can be mapped to any of the monitors via the video
distribution system (Bank 12). Figure 7-2 shows the typical response of the Golay
cell to a macropulse of the beam. This step ensures that the bunch length is minimal
at the location of the 8F03 viewer. The following steps ensure the bunch length is
minimal in the wiggler.
Figure 7-2: Golay signal shown on scope channel 1.
5. Push the Start button to perform a scan with the Happek device.
6. Save the data (for off-line analysis) by clicking the SAVE button on the lower left of
the Happek EPICS screen. A window will pop-up to add comments; enter the date
and any other relevant information pertaining to the scan.
7. Add a screen shot of the EPICS screen to the FLOG entry of the Miniphase.
8. Retract the ITV8F03 viewer and return the micropulse repetition frequency to 4.68
MHz and macropulse length to 250 s.
9. Adjust the vernier cavity gradient so that the CSR effect starts to show up at the
5F02 SLM. Typical response is to reduce the energy by ~0.2 MeV when maximizing
the Golay signal and then typically a fraction of 0.1 MeV to achieve the correct CSR
effect on the 5F02 SLM. Figure 7-3 shows the CSR effect “turned off”, and Figure 74 shows the CSR effect beginning to show up. There must to be tails on both sides
of the bunch beginning to show up as shown in Figure 7-4.
Figure 7-3: SLM5F02 image without CSR enhancement.
Figure 7-4: SLM5F02 image with CSR enhancement.
8.0
Adjust the Path Length
1. Map the 1G01 viewer to a monitor.
NOTE: Horizontal motion on this viewer corresponds to vertical motion on the
monitor screen.
2. Adjust Current Setpoint of the Pathlength Box Supply to set the pathlength (labeled
“H” on Figure 1-1). This is accomplished by centering the beam spot vertically on the
1G01 viewer. Adjust the Current Setpoint in 0.1 A increments to center the beam
spot vertically on the 1G01 viewer. It takes about a 1.2 A change in the current
setpoint to move the beam spot from one edge of the screen to another.
3. PROCEDURE COMPLETE.
9.0
Appendix I - Required EPICS/EDM screens (these have not been thoroughly checked 9/14/2010 C.T.)s
Useful screens/strip tools/monitors to have open and/or mapped.
1. drive laser parameters
2. drive laser Tekscope
3. Drivemaster
4. drive laser autocorrelator
5. Beamanizer
6. Tekscope B
7. Dump charge/current monitor
8. “phasetheinjector”
9. Injector RF 4-seater
10. video switcher
11. Viewer controls
12. RF Combo screens for zones 2,3, and 4
13. BPM combo screens
14. Happek controls
15. 4F and 5F corrector controls
16. 5F multipole controls
17. MPATH control screen
18. Beam Viewer Timing control screen
striptool
scope⇒monitor
FEL Main Menu⇒Drive Laser⇒Advanced Drive Laser
Master Control⇒Advanced Drive Laser Master Control
scope⇒monitor
scope⇒monitor
FEL Main Menu⇒Dumps⇒Beam
Current/Power⇒Beam Current
strip tool
FEL Main Menu⇒RF FEL Main Menu⇒Injector
Ops⇒Ops 4-seater⇒R4SEATER
FEL Main Menu⇒Viewer⇒Video Switcher
Control⇒FEL Video Switching System
FEL Main Menu⇒Viewer
FEL Main Menu⇒RF FEL Main Menu⇒Zone 2
Misc⇒RF Combo 4L02
FEL Main Menu⇒RF FEL Main Menu⇒Zone 3
Misc⇒RF Combo 4L03
FEL Main Menu⇒RF FEL Main Menu⇒Zone 4
Misc⇒RF Combo 4L04
FEL Main Menu⇒BPM⇒BPM Spikes⇒Combo⇒BPM
Absolute Spikes
FEL Main Menu⇒BPM⇒BPM Spikes⇒Combo⇒BPM
Relative Spikes
FEL Main Menu⇒Data Acq⇒Happek⇒IRUpstream⇒FEL Happek Interfermeter - IR(Upstream)
FEL Main Menu⇒Magnets⇒Magnet
Commander⇒4F⇒4F Correctors⇒Correctors for the
(4F) Region FEL Main Menu⇒Magnets⇒Magnet
Commander⇒5F⇒5F Correctors⇒Correctors for the
(5F) Region
FEL Main Menu⇒Magnets⇒Magnet
Commander⇒5F⇒5F Multipoles⇒Multipoles for the
(5F) Region
FEL Main Menu⇒Magnets⇒Box Supplies⇒Pathlength Box Supply⇒PathLength Power Supply
FEL Main Menu⇒Viewer⇒Beamviewer Timing
System⇒Beam View Timing System